<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<script>document.documentElement.offsetHeight</script>
</head>
<body>

<div style="height: 3000px; background: lightgreen;"/>

<div style="width: 4px; float: left; background: yellow;">
  A
  <span style="padding: 5px">
    <span style="float: left;" />
  </span>
  Z
</div>

</body>

</html>
